package jdk.observer;public class Test {    public static void main(String[] args) {        ProductList observable = ProductList.getInstance();        TaoBaoObserver taoBaoObserver = new TaoBaoObserver();        JingDongObserver jingDongObserver = new JingDongObserver();        observable.addObserver(jingDongObserver);        observable.addObserver(taoBaoObserver);        observable.addProduct("新增产品1");    }}